1. FIELD OF THE INVENTION
The field of the invention is fluid pressure booster devices of the type using a fluid pressure for boosting a master cylinder which is employed to operate brakes, clutches or the like of automobiles.
2. DESCRIPTION OF THE PRIOR ART
As has been disclosed in Japanese patent publication known fluid pressure booster devices of the type having a booster body, a booster piston accommodated in the booster body so as to define a boosting chamber, the booster piston moving forwards upon feeding of a fluid pressure to the boosting chamber to operate the master cylinder, a valve piston slidably accommodated in the booster piston and connected to an operating member, and a control valve which is capable of controlling connection and disconnection between the boosting chamber and a fluid pressure source or a fluid tank in response to forward and rearward movements of the valve piston in order to cause the booster piston to follow the movements of the valve piston.
In the mentioned type of booster devices, however, since the booster piston is constructed to follow the movements of the valve piston which is connected to the operating member, the valve piston has to move a stroke of the same amount as the booster piston and this makes it difficult to achieve an axially compact structure.